6. Using the rules of significant figures, calculate the following:

The balanced combustion reaction for C6H6 is 2C6H6(l)+15O2(g)⟶12CO2(g)+6H2O(l)+6542 kJ If 8.600 g C6H6 is burned and the heat pr

jenyasd209 [6]

Answer : The final temperature of the water is, $22.5166^oC$

Explanation : Given,

Mass of benzene = 8.600 g

Molar mass of benzene = 78 g/mole

First we have to calculate the moles of benzene.

$\text{Moles of benzene}=\frac{\text{Mass of benzene}}{\text{Molar mass of benzene}}=\frac{8.600g}{78g/mol}=0.1103mole$

Now we have to calculate the energy of combustion.

The given balanced chemical reaction is:

$2C_6H_6(l)+15O_2(g)\rightarrow 12CO_2(g)+6H_2O(l)+6542 kJ$

According to reaction,

As, 2 moles of benzene gives 6542 kJ of energy on combustion.

So, 0.1103 mole of benzene gives $\frac{6542 kJ}{2}\times 0.1103=360.7913kJ$ of energy on combustion.

Now we have to calculate the final temperature of the water.

Formula used : $q_w=m_w\times c_w\times \Delta T=m_w\times c_w\times (T_{final}-T_{initial})$

where,

$q_w$ = heat released = 360.7913 kJ = 36079.13 J

$m_w$ = mass of water = 5691 g

$c_w$ = specific heat of water= $4.18J/g^oC$

$T_{final}$ = final temperature = ?

$T_{initial}$ = initial temperature = $21^oC$

Now put all the given values in the above formula, we get:

$36079.13J=5691g\times 4.18J/g^oC\times (T_{final}-21^oC)$

$T_{final}=22.5166^oC$

Therefore, the final temperature of the water is, $22.5166^oC$

8 0

4 years ago

Energy that is associated with the position or composition of an object is called a kinetic energy. b potential energy. c therma

VLD [36.1K]

<h2>The required "option is b) potential energy".</h2>

Explanation:

The energy which is associated with the motion of the object is called kinetic energy.
The energy which is associated with the amount of heat released is known as thermal energy.
The energy which is released during a chemical reaction is known as chemical energy.

Therefore, option (a), (c), and (d) are incorrect.

The energy which is possessed by a stationary object or associated with the position of an object is called as potential energy.
Hence, the correct option is potential energy.

4 0

3 years ago

Calculate the number of hydrogen atoms present in 40g of urea, (NH2)2CO

tekilochka [14]

Answer: There are $16.14 \times 10^{23}$ atoms of hydrogen are present in 40g of urea, $(NH_{2})_{2}CO$ .

Explanation:

Given: Mass of urea = 40 g

Number of moles is the mass of substance divided by its molar mass.

First, moles of urea (molar mass = 60 g/mol) are calculated as follows.

$Moles = \frac{mass}{molar mass}\\= \frac{40 g}{60 g/mol}\\= 0.67 mol$

According to the mole concept, 1 mole of every substance contains $6.022 \times 10^{23}$ atoms.

So, the number of atoms present in 0.67 moles are as follows.

$0.67 mol \times 6.022 \times 10^{23} atoms/mol\\= 4.035 \times 10^{23} atoms$

In a molecule of urea there are 4 hydrogen atoms. Hence, number of hydrogen atoms present in 40 g of urea is as follows.

$4 \times 4.035 \times 10^{23} atoms\\= 16.14 \times 10^{23} atoms$

Thus, we can conclude that there are $16.14 \times 10^{23}$ atoms of hydrogen are present in 40g of urea, $(NH_{2})_{2}CO$ .

7 0

3 years ago

List the number of protons neutrons and electrons in 13/6 C

Charra [1.4K]

<h3>Answer:</h3>

Number of Protons = 6

Number of Electrons = 6

Number of Neutrons = 7

<h3>Explanation:</h3>

Number of Protons:

As the number of protons present in the nucleus are equal to the atomic number therefore, using periodic table one can easily find out the atomic number of C atom. Hence, C is present in group 14 and period 2 and having an atomic number of 6. Therefore, number of protons in C atom are 6.

Number of Electrons:

As shown in statement, C is not carrying any type of charge. It means this atom is neutral in nature. Which means, it is carrying the same number of electrons as the number of protons in order to give a neutral atom. Therefore, it contains 6 electrons.

Number of Neutrons:

Number of neutrons can be calculated using following formula,

No. of Neutrons = Atomic Mass - Number of Protons

As,

Atomic Mass = 13

So,

No. of Neutrons = 13 - 6

No. of Neutrons = 7

6 0

3 years ago

Read 2 more answers

Calvin shines a thin beam of light onto a material, and the light refracts. Which diagram best shows what happens to the light?

netineya [11]

Answer:

In goes in fractures (looks like broken angle)

Explanation:

6 0

3 years ago

Read 2 more answers